(Michelle R. Smith | AP file photo) This March 23, 2018, file photo shows an envelope containing a 2018 census letter mailed to a U.S. resident as part of the nation's only test run of the 2020 Census. The Supreme Court will decide whether the 2020 census can include a question about citizenship that could affect the allocation of seats in the House of Representatives and the distribution of billions of dollars in federal money.